1. Field of the Invention
This invention relates to a process for measuring the sheet resistance of a thin film such as a metal film or an ion implanted layer, and the reflectance of the thin film in the same apparatus either simultaneously or sequentially.
2. Description of the Related Art
Apparatus, such as a 4 point probe or an eddy current tool, is commercially available for measuring the sheet resistance of a thin film such as, for example, a metal film, For example, a 4 point probe apparatus to measure the sheet resistance of a thin film is available from KLA-Tencor as an Omnimap⊚ RS-100™ tool. An example of an eddy current tool to measure the sheet resistance of a thin film is the Omnimap⊚ NC110™ tool previously available from KLA-Tencor. Apparatus is also available commercially for the measurement of the reflectance of a thin film such as a metal film or an ion implanted layer, An example of such an apparatus is KLA-Tencor's ASET-F5 Tool.
While the use of separate measurement tools, to respectively determine the sheet resistance and the reflectance of a particular thin film, has been satisfactory in the past, the costs of individual tools and separate vacuum chambers to carry out the individual processes, as well as the fab footprint requirements, including the added process time, make it less and less attractive to carry out individual measurements of the sheet resistance and the reflectance of a thin film such as a metal film in separate apparatus.
In addition, carrying out the respective measurements in separate apparatus means that measurement spots on the thin film for reflectance measurements may not correlate with prior locations used for sheet resistance measurements made by either a 4 point probe or an eddy current to measure the sheet resistance of a thin film,